1. Field of Invention
The present invention relates to face masks and more particularly to means for preventing fogging of optical aids used by a wearer of a surgical face mask.
2. Technical Considerations
Face masks are generally worn to reduce the amount of contamination either exhausted from or inhaled by the wearer. Among these are masks of the sterile, surgical variety, necessities for hospital operating rooms. Surgical face masks are worn by surgeons and others around an operation to substantially prevent the contamination and infection of the patient from the wearers during operations. Effective and comfortable masks are available which are both disposable and nondisposable. The advantage of disposability is the elimination of the expensive sterilizing procedure and inherent danger of cross-contamination.
Surgical masks are generally lightweight in construction and contain several features designed for adaptation to an individual wearer's features. There is often incorporated within the mask, along the upper edge, an elongated, deformable metal strip having sufficient stiffness to retain any shape given it. In this way, the upper portion of the mask may be contoured to the wearer's face to improve the upper edge fit. A relatively thin strip of soft foam material is sometimes found along this upper edge to increase the comfort of the wearer.
Although the upper edge may be contoured in a variety of facial shapes to most closely approximate the wearer's features, it is inadequate to prevent the wearer's breath from rising between his or her face and the mask. Since these masks are not designed to obstruct breathing, but rather to provide a breath filter, some breath exhausts through the upper portion of the mask into the vicinity of the wearer's eyes. The breath being warm and moist, holds fluid vapor which readily condenses on cooler objects. Such cooler objects may be present in the air-conditioned operating rooms in the form of glass lenses of optical aids used by the surgeons and assistants. Such optical aids include spectacles, surgical loupes and surgical microscopes.
The exhaust of exhaled breath is resisted to some degree by the mask itself, prompting some breath to flow under the mask edges. Because warm air rises, the wearer's breath also has a natural tendency to rise under the upper mask edge and through the upper mask surface area producing fogging of the optical aids positioned in the vicinity of the wearer's eyes. This obscuration of the wearer's vision is a nuisance at best and a hazard at worst. This shortcoming of the prior art mask often requires the surgeon to pause to clear the lenses of condensation interfering with his or her vision. The necessity for clear vision during surgical procedures as well as the time expediency element has fostered a need for preventing such fogging.
One attempt to eliminate fogging has been the chemical treatment of optical lenses to reduce condensation to vapor thereon. Such attempts deal with the problem rather than eliminating it. The most economical and straightforward approach would be to prevent the moist air from the breath of the wearer of the optical aids from contacting them. Thus, some surgeons have resorted to the expediency of using strips of adhesive tape to seal the upper edge of the mask against their face. The tape by necessity adheres to the tender skin beneath the eyes. Since a surgeon may operate several times in one day, the tape may be removed numerous times causing severe chafing and irritation in this area. Aside from the chafing and inconvenience to the surgeon, this means poses possible problems with allergy to the tape in some persons, and even so-called "hypoallergenic" tapes can cause skin irritations. The serious import of the fogging effect for both the wearer and the patient has thus necessitated an effective method of and means for eliminating this problem.